1. Field of the Invention
The invention relates to a motor-driven roller blind comprising an apron formed by a juxtaposition of slats at least hingedly joined to each other and the ends of which move in side slides, this apron rolling up onto and unrolling from a winding shaft inside which is accommodated a tubular-type driving gear-motor. This roller blind may eventually also be provided with means providing an electrical signal representative of the movement of the apron and an electrical-signal processing unit capable of acting on the running of the driving gear-motor, viz. to control the stopping of same in the event an obstacle is present.
This invention will find its application in the field of the closing devices, such as roller blinds.
2. Description of the Prior Art
There is already known a roller blind corresponding to the above description. Thus, this motor-driven roller blind comprises an apron rolling up onto or unrolling from a winding shaft which is in this case rotatingly driven by tubular-type electric driving means, viz. a gear-motor, which is as a matter of fact accommodated inside the winding shaft. It should be noticed that this winding mechanism for the apron of the roller blind is generally arranged in a box under which extend slides serving for guiding the side ends of the slats the apron of comprised of, this during unrolling or rolling up of this latter.
This roller blind is also provided with means providing an electrical signal representative of the movement of the apron, these means being substantially comprised of a pulley onto which is wound a flexible member, such as a cord, the free end of which is connected to the end slat of the apron. Thus, during unrolling of this apron, this gives rise to the unwinding of the cord and the driving of said pulley. Associated with this latter are springy means ensuring the re-winding of the cord onto the pulley during the rolling up of the apron. There is also provided a signal generator mechanically connected to the spindle of the pulley and providing an electric voltage representative of the speed of rotation of the pulley. It is specified that this signal generator may preferably be in the shape of a Hall effect sensor, such as a synchronous motor used as a generator. According to another embodiment, there is also foreseen to use as signal generator a constraint gauge combined with a spring gradually tensioned by the rotation of the pulley.
In addition, there should be noticed the presence, at the level of this roller blind, of a logical processing unit capable of operating in learning mode and working mode, by sampling, and comprising means for storing, in learning mode, the value samples corresponding to the measured signal samples and means for comparing, in working mode, the stored value samples to value samples obtained in working mode. Thus, this logical unit comprises means for sampling the electric signal provided by the signal generator.
As a matter of fact, the main disadvantages experienced with a roller blind as described above are mainly due to the structure of the means providing an electrical signal representative of the movement of the apron. More particularly, such means are first of all bulky as far as they require the installation, at the level of the box of the roller blind, of a pulley onto which is capable of rolling up the transmission member formed by the cord. Furthermore, with that pulley should be associated the signal generator in the shape of a synchronous motor. As a matter o fact, this unit is positioned at the end of the winding shaft of the apron, which is not always feasible, due to lack of space.
In addition, the mechanical connection between the end slat of the apron and the pulley is a cause for operating trouble. Viz., the cord forming this transmission member can at any time get jammed through clamping either at the level of the roller blind itself or at the height of the door or window closed by this roller blind. Not taking into consideration that this cord is accessible to the user, which obviously increases the risks of incidents.
There is furthermore known a roller blind which uses, as means providing an electrical signal representative of the movement of the apron, first of all means for detecting the linear translation motion of the apron, in the shape of a roller rubbing against the surface of said apron and converting the linear displacement motion of the blind into a rotary motion. Furthermore, there are provided coding means, in the shape of a coding wheel provided with a number of peripheral and radial notches which is integral with said friction roller and driven by this latter. Associated with this coding wheel is a system for detecting the information provided by this latter, viz. an optoelectronic sensor, which is capable of detecting the passing of the notches of said coding wheel and providing an electrical signal. This latter is then processed at the level of a central processing unit.
There is also provided a roller blind apron sensor for detecting its arrival in the upper position. This sensor is carried out as a spring-pulled roller resting onto the surface of the apron and leaving this surface at the upper travel end in order to operate a microcontact controlling the stopping of the apron driving gear-motor.
It is foreseen to arrange such means providing an electrical signal representative of the movement of the apron at the upper end of a side slide or even at the supper end of each side slide a roller blind is provided with.
Although such means capable of providing an electrical signal representative of the movement of the apron are particularly bulky like those described first above, this is not their major disadvantage. They are indeed in no way adapted to roller blinds the apron of which is comprised of slats which are not only hingedly joined to each other, but also telescopic, so that the possibility exists of obtaining an openwork position as is the case in most domestic roller blinds. The roller rubbing against the surface of said apron is indeed necessarily arranged at the upper end of this latter. Hence, it can detect a change in the movement of this apron only when all the slats located under this roller have been piled up and tightened against each other.
In addition, in this case one also finds the mechanical connection which is indispensable between the means providing an electrical signal representative of the movement of the apron and this latter. Now, such a mechanical connection is liable to dysfunctions, viz. in the course of time, which cannot be accepted for a product, such as a roller blind, with a long lifetime.